Clinicians often use ventilators or breathing circuits to assist patient breathing or to otherwise treat respiratory ailments. Ventilators and breathing circuits provide mechanical assistance to patients having trouble breathing on their own and are used to deliver gases and medications. A breathing circuit may be coupled to or include a positive pressure source, such as a container of a pre-compressed gas or a ventilator, to deliver a flow of pressurized gases to the lungs of a patient. When the overpressure is released, the patient will exhale due to the elasticity of the lungs (in many devices the sequence can be reversed, i.e., a patient attempting to exhale during the overpressure can cause the overpressure to release). At times, the breathing circuit may be a simple, hand-operated bag valve mask to fit over a patient's nose, mouth or both. Some breathing circuits are more complicated and can include a set of additional breathing components, such as nebulizers, heat and moisture exchange (HME) units, and others, disposed between the pressure source and patient.
Breathing circuits are robust but may contain leaky interfaces at locations where components are coupled to the patients, such around masks, or between chambers within the components themselves, such as within HME units. These interfaces are of often leaky as a result of variable compressions between elements of the interface. Variable compression interfaces share the common feature that they provide likelihood for ambient air or other gases to unintentionally mix with the pressurized gases because the interfaces can be leaky. Ambient air or other gases introduced into the circuit can contain unwanted airborne products such as microbials that can spread to the patient. Additionally, leaky interfaces can spread microbials from the patient to the caregiver.
Leaky interfaces that result in unintended mixing of fluids and unwanted penetration of microbials are not limited to breathing circuits. Another example of a variable compression interface includes a duck bill or wiper seal interface with a patient often used with a surgical trocar, which provide an entry point to introduce laparoscopic instruments into a patient to provide a less invasive surgery. Additional examples of variable compression interfaces can be readily determined that reduce the efficiency of fluid flow or permit the penetration of unwanted particles.